In recent years, there have been many liquid crystal display devices each employing a backlight that includes, for the purpose of reducing the thickness, a side edge-type (also called side light) light guide plate for emitting light from a light source in the form of a plane.
Patent Literature 1 discloses a lighting device, which is an example of such a side edge-type light guide plate. FIG. 11 is a plan view illustrating the lighting device of Patent Literature 1. As illustrated in FIG. 11, a lighting device 100 disclosed in Patent Literature 1 includes (i) a light guide plate 110 constituted by a plurality of light guides 111 arranged in a line and (ii) a plurality of light sources 101 provided so as to correspond to the respective light guides 111 of the light guide plate 110 and emit light to the light guides 111. On the bottom side of the light guide plate 110, there is provided a reflection sheet (not illustrated). Further, there is a gap 103 between adjacent ones of the light guides 111, which gap is made up of an air layer of 0.1 μm or larger. This configuration makes it possible to carry out a preliminary impulse display.
However, in a case of using such a side-edge type light guide plate, it is difficult to fasten the side edge-type light guide plate.
In view of the circumstances, Patent Literature 2 discloses an attachment structure for a light guide plate, which is an example of how to fasten a side edge-type light guide plate. FIG. 12 is a plan view illustrating the attachment structure for attaching a light guide plate 210 in a lighting device 200 of Patent Literature 2. As illustrated in FIG. 12, the attachment structure for the light guide plate 210 disclosed in Patent Literature 2 is such that, in the lighting device 200 configured such that light emitted from the light source 201 enters a single light guide plate 210, a small positioning hole 206, which is in a light introduction frame 202 of the light guide plate 210, and a boss 207, which is provided to an attachment base (not illustrated) to which the light guide plate 210 is to be attached, fit together. According to this configuration, a light introduction frame 202-side portion of the light guide plate 201 is positioned with respect to the light source 201. This makes it possible to reduce luminance unevenness. Further, by providing the boss 207 on a perpendicular bisector of the light introduction frame 202, a luminance uneven area is canceled out by light that comes diagonally from the left and the right. This makes it possible to effectively use a large part of the light guide plate 210 as a light emitting area 211.